『Abstract
　Globally, hypoxic areas (＜63 mmol O2 m^-3) in coastal waters are increasing in number and spatial extent. One of the largest coastal hypoxic regions has been observed during the summer in the bottom-water of the Louisiana continental shelf. The shelf receives the sediments, organic matter, and nutrient exported from the Mississippi River watershed, and much of this material is ultimately deposited to the sea floor. Hence, quantifying the rates of sediment-water dissolved inorganic carbon (DIC), oxygen (O2), and nutrient fluxes is important for understanding how these processes relate to the development and maintenance of hypoxia. In this study, the sediment-water fluxes of DIC, O2, nutrients, and N2 (denitrification) were measured on the Louisiana shelf during six cruises from 2005 to 2007. On each cruise, three to four sites were occupied in or directly adjacent to the region of the shelf that experiences hypoxia. DIC fluxes, a proxy for total sediment respiration, ranged from 7.9 to 21.4 mmol m^-2 day^-1 but did not vary significantly either spatially or as a function of bottom-water O2 concentration. Overall, sediment respiration and nutrient flux rates were small in comparison to water-column respiration and phytoplankton nutrient demand. Nitrate fluxes were correlated with bottom-water O2 concentrations (r=0.69), and thee was evidence that decreasing O2 concentrations inhibited coupled nitrification-denitrification. Denitrification rates averaged 1.4 mmol N m^-2 day^-1. Scaled to the area of the shelf, the denitrification sink represented approximately 39％ of the N load from the Mississippi River watershed. The sediment-water fluxes reported from this study add substantial information on the spatial and temporal patterns in carbon, O2, and nutrient cycling available for the Louisiana continental shelf and, thus, improve the understanding of this system.

Keywords: Sediment-water DIC; O2 and nutrient flux; Denitrification; Hypoxia; LOUISIANA shelf』

Introduction
Materials and methods
　Study site
　River discharge and hydrographic data
　Sediment-water fluxes
　Sediment bulk analyses
　Phytoplankton biomass and production rates
　Statistical analyses
Results
　Mississippi river discharge and shelf hydrographic conditions
　Sediment characteristics
　Sediment-water fluxes
　Relationships among sediment-water fluxes and other variables
　Water-column phytoplankton biomass and primary production
　Sediment-water fluxes in comparison to water-column primary production
Discussion
　Methodological considerations for sediment-water fluxes
　Characterization of sediment-water fluxes on the Louisiana shelf
　DIC and O2 fluxes
　N, P, and Si fluxes
　Denitrification
　Zones of similarity
　An updated conceptual model of the role of the sediments in system metabolism on the Louisiana continental shelf
Acknowledgments
References